Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Assets [Abstract]
Restricted cash	$ 92	$ 127
Accounts receivable	751	709
Securitized regulatory assets	497	577
Other assets	140	142
Total Assets	17,799	17,493
Liabilities [Abstract]
Current portion long-term debt, including, capital leases	474	470
Other current liabilities	241	283
Securitization bonds	391	479
Other long-term liabilities	104	115
Notes, Loans and Financing Receivable, Net, Noncurrent	4	4
Variable Interest Entity Securitization [Member]
Assets [Abstract]
Restricted cash	92	107
Accounts receivable	37	34
Securitized regulatory assets	497	577
Other assets	9	10
Total Assets	635	728
Liabilities [Abstract]
Accounts payable and accrued current liabilities	12	14
Current portion long-term debt, including, capital leases	168	164
Other current liabilities	48	55
Securitization bonds	391	479
Other long-term liabilities	7	7
Total Liabilities	$ 626	$ 719